Monolithic bypass diode and photovoltaic cell with bypass diode formed in back of substrate

Abstract

An apparatus and method for making a solar cell assembly. An apparatus in accordance with the present invention comprises a substrate, at least a first solar cell, coupled to a first side of the substrate, the first side of the substrate to be exposed to light such that the at least first solar cell generates a current when exposed to the light, and a bypass diode, formed on a second side of the substrate, the second side of the substrate being substantially opposite the first side of the substrate, such that the bypass diode is monolithically integrated with the at least first solar cell.

What is claimed is: 
     
       1. A solar cell assembly, comprising:
 a germanium (Ge) substrate; 
 at least a first solar cell, coupled to a first side of the Ge substrate, the first side of the Ge substrate to be exposed to light such that the at least first solar cell generates a current when exposed to the light; and 
 two Schottky barrier bypass diodes connected in series, the two series connected Schottky barrier bypass diodes being connected in anti-parallel with the at least one solar cell, and the two series connected Schottky barrier bypass diodes being monolithically integrated with the Ge substrate and formed in a single recess or on a surface of a second side of the Ge substrate, the second side of the Ge substrate being substantially opposite the first side of the Ge substrate, such that the two series connected Schottky barrier bypass diodes reduce the leakage current in the solar cell assembly. 
 
     
     
       2. The solar cell assembly of  claim 1 , wherein the two series connected Schottky barrier bypass diodes are formed in the Ge substrate. 
     
     
       3. The solar cell assembly of  claim 1 , wherein the at least first solar cell is a multi junction solar cell. 
     
     
       4. The solar cell assembly of  claim 2 , wherein the two series connected Schottky barrier bypass diodes are connected to a solar cell resident on a solar cell assembly other than the solar cell assembly where the two series connected Schottky barrier bypass diodes are formed. 
     
     
       5. The solar cell assembly of  claim 1 , wherein the two series connected Schottky barrier bypass diodes are grown on the second side of the Ge substrate. 
     
     
       6. The solar cell assembly of  claim 1 , wherein the Ge substrate is etched away prior to forming the two series connected Schottky barrier bypass diodes. 
     
     
       7. The solar cell assembly of  claim 6 , wherein the two series connected Schottky barrier bypass diodes are electrically isolated from the at least one solar cell. 
     
     
       8. A method for making a solar cell assembly, comprising:
 forming at least one solar cell on a first side of a germanium (Ge) substrate, the first side of the Ge substrate to be exposed to light such that the at least first solar cell generates a current when exposed to the light; 
 forming two Schottky barrier bypass diodes connected in series, the two series connected Schottky barrier bypass diodes being connected in anti-parallel with the at least one solar cell, and the two series connected Schottky barrier bypass diodes being monolithically integrated with the Ge substrate and formed in a single recess or on a surface of a second side of the Ge substrate, the second side of the Ge substrate being substantially opposite the first side of the Ge substrate, such that the two series connected Schottky barrier bypass diodes reduce the leakage current in the solar cell assembly. 
 
     
     
       9. The method of  claim 8 , wherein the two series connected Schottky barrier bypass diodes are connected to a solar cell resident on a solar cell assembly other than the solar cell assembly where the two series connected Schottky bypass diodes are formed. 
     
     
       10. The method of  claim 8 , wherein the two series connected Schottky barrier bypass diodes are formed in the Ge substrate. 
     
     
       11. The method of  claim 8 , wherein the two series connected Schottky barrier bypass diodes are formed using a schottky barrier. 
     
     
       12. The method of  claim 8 , wherein the at least first solar cell is a multi junction solar cell. 
     
     
       13. The method of  claim 8 , wherein the two series connected Schottky barrier bypass diodes are grown on the second side of the Ge substrate. 
     
     
       14. The method of  claim 8 , further comprising etching the Ge substrate away prior to forming the two series connected Schottky barrier bypass diodes. 
     
     
       15. The method of  claim 14 , wherein the two series connected Schottky barrier bypass diodes are electrically isolated from the Ge substrate.